Who can I contact if I have a question or comment about a nautical chart?

What is a nautical chart?

A nautical chart is a two-dimensional graphic of a 3-D world. It represents part of the spherical earth on a plane surface. It shows water depth, the shoreline of adjacent land, prominent topographic features, aids to navigation, and other navigational information.

The navigator uses the chart to plot courses, ascertain positions, and view the relationship of the ship to the surrounding area. It helps the navigator avoid dangers and arrive safely at the desired destination.

What is the difference between a map and a chart?

A nautical chart presents the coastline taking into account varying tidal levels and water forms. A map, on the other hand, emphasizes landforms.

Where can I learn more about the different symbols on a nautical chart?

U.S. Chart No. 1 describes the symbols, abbreviations and terms used on all NOAA, NGA and international nautical charts, as well as the symbols used to portray NOAA ENC® charts on an ECDIS.

Why do you offer different chart products?

Not everyone needs the same print quality; it depends on the chart’s intended use. We want to maximize consumer choice. For instance, we want to allow the free market to meet the needs of customers who are not required to adhere to the requirements of the International Convention for the Safety of Life at Sea (SOLAS). In addition, we think one of the most important features of a chart is that it is up-to-date, and we want to support on-board chart printing for vessels with that capability.

What is the difference between an ENC and an RNC?

A raster navigational chart (RNC) is an accurate digital image comprised of pixels, displayed on an electronic screen. Each pixel has a unique color or it has no color. The pattern of the colored and the empty pixels gives shape to the individual features of the chart.

An electronic navigational chart (ENC) is navigational features in a vector format. That is achieved by digitizing each feature’s geometry into a specific object.

See the RNC-ENC Comparison page for a more in depth discussion of the differences between these products.

How can I figure out which chart I need?

Visit the NOAA nautical chart catalog - zoom, pan and then click on the chart outline that covers the area that you want. Paper and raster charts generally are identified with five digit numbers, while ENCs are identified by characters like “US3CA85.”

Why do I need an updated chart?

Coast Survey apply tens of thousands of changes to NOAA charts every year. Some changes are minor, but many are critical to safe navigation. Those critical updates can include new shoals, wrecks, and obstructions, and the latest changes to navigation aids. Additionally, shorelines are changing all the time, due to natural forces, storms or infrastructure improvements.

Where do I get chart updates?

The United States Coast Guard issues Local Notices to Mariners, providing up-to-date important navigational information. The National Geospatial-Intelligence Agency issues weekly the U.S. Notices to Mariners for larger vessels, such as those operating in 12 feet of water or more. You can also find information about chart corrections on NOAA’s Weekly Chart Update webpage.

Where can I get a paper chart?

Paper nautical charts can be purchased from a NOAA certified chart agent. These agents have access to each one of our thousand nautical charts, and are required to make them all available for purchase. It is easy to order a chart online or by telephone, and have the chart delivered to your door.

How can I become a NOAA certified chart agent?

How can I print a chart at home?

You can download the full-size nautical chart (pdf) to your local computer and print the chart on a large format plotter. Alternatively, you can print a chart on a standard 8.5 x 11” printer by downloading a BookletChart™.

How can I get a copy of an old NOAA chart?

Are there copyright restrictions for printing out a chart, using it in a publication, or repackaging chart images to create new products?

NOAA’s nautical charts are in the public domain. You may use then for any purpose free of charge, with two exceptions:

Paper charts that fulfill chart carriage requirements for regulated commercial vessels under Titles 33 and 46 of the Code of Federal Regulations must be purchased from NOAA-certified vendors.

Commercial printers must be certified by NOAA to sell navigational charts and publications that are “published by the National Ocean Service.” Information on becoming a certified chart distributor can be found on our Business and Partnerships Opportunities webpage.

When republishing a NOAA chart, we request a citation, but we do not require it. The preferred format for citation: “Provided by NOAA Office of Coast Survey, nauticalcharts.noaa.gov.” More information on how copyrights apply to government publications can be found at U.S. Government Works.

What is an electronic navigational chart?

Electronic navigational charts (ENC) are vector data sets that support all types of marine navigation. More information can be found on our NOAA ENC® webpage.

What are ECS and ECDIS?

Electronic chart systems (ECS) encompass any electronic system that uses digital chart data. The chart data can be vector or raster. No specific format is currently defined, although many ECS can use NOAA ENC data. The Radio Technical Commission for Maritime Services (RTCM) has published Standard for Electronic Chart Systems, RTCM 10900.6.

Electronic chart display and information systems (ECDIS) are certified to meet a suite of international standards:

How can I obtain NOAA ENCs?

NOAA ENCs may also be obtained from NOAA certified ENC distributors who provide global ENC distribution services. These companies may charge a fee for this service.

Is a NOAA ENC simply a copy of the paper chart?

Although the sources used to compile and maintain paper charts and ENCs are the same, a paper chart is a static representation, while an ENC has layers of data that can be turned on and off in the chart display and interact with the navigation system to provide warnings and alarms of dangers. The display of ENCs is also often simpler and less cluttered than the portrayal rendered on a paper chart.

What are the sources used in compiling NOAA ENCs?

NOAA uses a number of sources in compiling NOAA ENCs. These include U.S. Army Corps of Engineers surveys, drawings and permits; U.S. Coast Guard Local Notices to Mariners; National Geospatial-Intelligence Agency Notices to Mariners; NOAA hydrographic surveys; the largest scale paper chart of the area; and other information provided by a variety of public and private sources.

How current is the NOAA ENC?

All NOAA ENCs are under continuous maintenance. As new source data is received by NOAA, it is evaluated, compiled, and released to the public on a weekly basis. This includes relevant USCG Local Notice to Mariners and NGA Notice to Mariners.

Incremental updates to the current edition of ENCs are issued weekly. Once the number or size of the updates becomes large, a new edition of an ENC is released. This may occur at any time and is not tied to the publication of a new edition of the corresponding paper chart.

Do ENCs meet U.S. Coast Guard carriage requirements?

Official NOAA ENCs meet U.S. Coast Guard Carriage requirements, as defined in Title 33 and Title 46 of the U.S. Code of Federal Regulations (CFR).

What hardware and software is required operate NOAA ENCs?

Display of NOAA ENC depends on navigation software such as an ECDIS, which conforms to international standards. However, the NOAA ENC is not dependent on unique operating systems or navigation software. Since it is provided in a standard format, any navigation software company that wants to support NOAA ENC data can create applications that use it.

Does NOAA provide any viewing software?

You can see a seamless display of NOAA ENCs with the NOAA ENC® viewer. Screen captures of the ENCs displayed on this site do NOT fulfill chart carriage requirements for regulated commercial vessels under Titles 33 and 46 of the Code of Federal Regulations.

What does the date entry mean on the NOAA ENC download page?

Each ENC has an Update Application Date, an Issue Date and various Cleared Dates. For more information, see the ENC Dates webpage.

Do NOAA ENCs have edition numbers or print dates like paper charts?

Yes. Every NOAA ENC starts with a file header that contains information about that particular ENC, including edition number, issue date, and update application date. Edition numbers start at one (1) the first time an NOAA ENC is issued and increases sequentially.

What does the file name of the NOAA ENC mean?

The NOAA ENC file name format is specified in the International Hydrographic Organization Transfer Standard for Digital Hydrographic Data, Special Publication S-57.

The first two characters, US, indicate that the U.S. Office of Coast Survey, NOAA, produced the NOAA ENC.

The third character indicates the "navigational purpose" of the NOAA ENC as defined in S-57, a rough indicator of the scale of the NOAA ENC: 1-overview; 2-general; 3-coastal; 4-approach; 5-harbor; 6-berthing.

Coast Survey defines the remaining characters left of the dot.

The fourth and fifth characters are the two-letter code for the state where the ENC is located (e.g., TX for Texas, NY for New York, etc.).

The next two characters are the NOAA ENC number.

The final “M” character indicates that the NOAA ENC is in metric units.

The file extension used for a base new edition NOAA ENC is, ".000." The first update for a base cell will be ".001," the next ".002" and so forth.

What are the other files included with the NOAA ENC?

CATALOG.031 - lists of the cells and ancillary files that are included in an NOAA ENC "exchange set."

README.TXT - lists all of the NOAA ENCs with their corresponding paper/raster chart number, title and other information.

Ancillary files - text files that are analogous to chart notes on the paper chart or possibly information from the United States Coast Pilot.

Image files - a picture that links to a feature(s) on the NOAA ENC, such as a picture of a bridge.

What is the difference between the NOAA ENC and the Digital Nautical Chart (DNC™)?

The NOAA ENC is based on the International Hydrographic Organization Transfer Standard for Digital Hydrographic Data, Publication S-57 and is approved by the International Maritime Organization for SOLAS class vessels to use for navigation in ECDIS. The DNC uses the Vector Product Format, which is a NATO standard for digital military map and chart data. They are both vector format charts and are based on NOAA nautical charts, just in different formats. The NOAA ENC, however, has certain critical features such as aids to navigation and channel limits created from larger scale, more accurate information than can be obtained by digitizing a paper or raster nautical chart. More information about DNCs can be found at the National Geospatial-Intelligence Agency website.

How do paper charts and RNCs compare?

The paper nautical chart is the fundamental tool of marine navigation. It has served for hundreds of years to convey information about the marine environment and for voyage planning and monitoring.

The NOAA RNC® exactly reproduces the familiar paper chart image. All chart information is available to mariners in a picture they are experienced at using.

How does the RCDS Performance Standard differ from the ECDIS Performance Standard?

The RCDS Performance Standard is identical to the ECDIS Performance Standard except where the difference between raster data and vector data requires a change.

RCDS does not have the automated alarms triggered by chart data that ECDIS provides nor could one reduce clutter by turning off chart objects. However, mariners would still have real time positioning, automatic updating and any alarms entered manually (off-track alarm, obstructions...). In addition, the familiar chart image would minimize training time and would allow mariners to use their existing navigation skills immediately.

How does RCDS deal with charts of different map projections and on different datums?

Metadata included with the RNC's identifies the projection and datum for each chart. The navigation software then converts positioning system information into the chart's projection and datum in real-time. If a chart's datum is unknown, the RNC metadata includes the parameters necessary to map geographic positions to RNC pixel locations calculated from the grid intersections printed on the chart.

How can raster charts replace paper charts when only a portion of a chart can be seen at any one time?

RCDS offers exactly the same field of view capability as ECDIS which has already been accepted by the IMO/IHO. Both RCDS and ECDIS specify a 270mm x 270mm screen size. Whether displaying a 1:40,000 scale RNC or 1:40,000 scale NOAA ENC® data, the width of the computer screen will only show approximately 5.8 nm.

RCDS and ECDIS deal with a computer's limited field of view in a similar way. RCDS users load the next smaller scale chart. ECDIS users zoom out and let the software suppress information and resize the remaining text and symbols -- in essence creating a smaller scale chart dynamically. Also, the ability to pan across a chart or to open multiple charts of different scales at the same time gives RCDS and ECDIS increased viewing capability.

How can one plot a course and navigate that course when it crosses several charts which may be of different projection, scale and datum?

Advanced RCDS software automatically switches charts when the vessel arrives at the edge of the present chart. The new chart is displayed in a scale as close to the previous chart as possible. The datum issue is addressed above. Projection differences are automatically accommodated by advanced RCDS software.

Does chart clutter make a RCDS unusable?

RNC's are exact copies of paper charts and contain all the detail of those original charts. Hydrographic offices had worried that this would appear "cluttered" when displayed on a computer monitor. However, users are reporting that "chart clutter" is not a serious problem with raster charts.

How are chart notes and legends found on a raster chart?

Hydrographic offices provide the coordinates of a rectangle surrounding each note, legend, tide box or channel depth table. They also provide reference point coordinates for each note. RCDS software places an unobtrusive (or invisible!) icon at the reference point. When the icon is "picked" by the mariner, a second small window on the chart opens, displaying the note. This method would allow notes to be displayed automatically as a mariner's ship approaches the coordinates of the reference points.

Can text and symbols be resized (rescaled) when one zooms in and out on a raster chart?

No. Text and symbols will be enlarged or reduced as one zooms in and out. If this results in text that is too small or too large to read, it means that you are operating out-of-scale and should switch to a different scale chart.

Can the mariner limit the information that is displayed on an RNC?

No. Only the entire RNC chart image can be displayed, unlike ENCs, in which certain layers of information may be turned on or off.

Can data be interrogated with RNCs as it can with ENCs in an ECDIS?

No. RNCs cannot be interrogated. An RNC is merely an electronic picture of a paper chart. However, since the RNC displays all of the paper chart, most information is already displayed and the RNC does not need to be interrogated.

What kind of automatic alarms and indicators does an RCDS support?

RCDS issues automatic indicators when an RNC is being displayed over scale, when a larger scale chart is available and when the chart is on a different reference system from the positioning system. RCDS issues automatic alarms for exceeding an off-track limit, deviating from a route, approaching a critical point, using a chart on a different geodetic datum, approaching a critical point/line/area and for an RCDS malfunction.

RCDS allows mariners to enter points, lines and areas to designate other alarm items. A mariner may enter obstructions, navigable limits (rough safety contours), prohibited areas, etc. anywhere on a chart or on any chart. These are monitored by RCDS software and alarms can be triggered even though a particular chart is not being displayed at the time an alarm feature is approached.

Is it possible to integrate a radar presentation with the RCDS display?

Yes. Navigation software now filter the radar picture so that it and the raster display are legible.

Do NOAA RNCs have daytime and nighttime colors like ENCs in ECDIS?

No, NOAA has specified only one color pallet for RNCs, which is similar, but not exactly the same, as the colors seem on NOAA paper charts.

I downloaded RNCs to my local computer. When I double click on the file and nothing happens. Why?

RNCs are created in a specific international format, which cannot be displayed with the ordinary text or image processing software found on most computers. There are many RNC display software packages available commercially. NOAA does not create of distribute software to display its RNC or ENC products.

What is hydrography?

The International Hydrographic Organization defines hydrography as “the branch of applied science which deals with the measurement and description of the physical features of the navigable portion of the earth’s surface [seas] and adjoining coastal areas, with special reference to their use for the purpose of navigation.”

What is the purpose of a hydrographic survey?

A hydrographic survey supports a variety of activities: nautical charting, port and harbor maintenance (dredging), coastal engineering (beach erosion and replenishment studies), coastal zone management, and offshore resource development. Hydrographers use sound (SONAR) and light (LIDAR) to ‘see’ the bottom of the ocean. The primary information obtained by hydrographic surveys are water depth and potential existence of dangers to navigation. A hydrographic survey also helps determine the nature of the sea floor material (i.e. sand, mud, rock), which is important for anchoring, dredging, structure construction planning, pipeline and cable routing, and fisheries habitat mapping.

Where can I find bathymetric and hydrographic data?

Where can I find information on submerged wrecks and obstructions?

Information for submerged wrecks and obstructions in the coastal waters of the United States, including geographic coordinates, can be obtained from NOAA’s Automated Wreck and Obstruction Information System (AWOIS). AWOIS contains supplemental textual information including coordinates for items of navigational significance charted on NOAA nautical charts but is not designed to be a comprehensive list of all shipwrecks in any given area. Note: AWOIS data is no longer updated by NOAA. It is provided for informational purposes only and is not an authoritative source of information.